In the brewing process, one of the most important ingredients that is often overlooked is the yeast. We always use yeast to create our tasty brews, so why not know more about what yeast has to offer? With the variety of yeast as expansive as beer styles, there are hundreds of different combinations just waiting to be tried.BasicsYeast is an organism related to mushrooms that, for the purposes of brewing, consumes sugars and, as a byproduct, creates carbon dioxide, alcohol, and flavor/aroma esters. The two largest groups are lager and ale yeasts. Lager yeast is bottom-fermenting and generally ferments at cooler temperatures. Ale yeast is top-fermenting and generally used at warmer temperatures. Lager is a German term that actually means “cold storage,” so any beer can be lagered–but not all beers are lagers. Inside the larger yeast subset, there are varieties from all over Europe that would be used in Czech-style pilsners and German Schwarzbiers. There are also American varieties that are used in “steam” or warm lager beers and the now-popular India Pale Lager. Ale yeasts have a larger variety of subcategories; including English, West Coast American, East Coast American, Belgian and German. Of course, as with all aspects of homebrewing, these generalizations do not apply to every yeast and rules are supposed to be broken.SelectionDeciding what yeast to use for a particular beer style is usually as simple as following a recipe. Unfortunately, it can be a bit boring if you use the same American ale yeast on everything you brew. Instead of going crazy and throwing a Bohemian Pilsner yeast into your IPA, a safer first experiment would be to use a British ale yeast instead of the American; thus allowing you to see the subtle differences between the two ales. Another option is to read up on a bunch of different yeast strains. The yeast companies do a very good job of describing the different flavor profiles of the yeast in their inventory. You can find all of this information on the Internet or at your local homebrew shops. Reading what flavors a yeast can produce will help in the selection process, but you will never know if it works until you try.The FutureThe magic of fermentation creates the majority of the flavors and all of the alcohol in the beer styles we know and love. We as brewers only attempt to create an environment for the yeast that is healthy and ensures that they will be happy. With the beer industry trying new things and creating different styles, remember:As homebrewers, we have the ability to do more experimentation. Continuing to push the envelope can be risky and not every brew is going to be the greatest, but once the experiment comes out great, that is worth all of the effort.